Simulated performance of an energy storage and return prosthetic ankle based on cams and miniature hydraulics

Prosthetic feet are limited in their ability to mimic the energy-recycling behavior of an intact ankle, negatively affecting lower-limb amputees’ gait terms metabolic cost and walking speed. To overcome these weaknesses, a novel prosthetic ankle based on hydraulics is described here. The joint drives two cams, which turn drive hydraulic rams. One cam-ram system captures negative work done from foot-flat until maximum dorsiflexion, by pumping oil into accumulator, while other returns positive during push-off providing forward propulsion through fluid flowing accumulator ram. Simulation results promising: total over cycle (i.e., amount energy available be stored), 78% returned, mainly push-off; 14% carried for future cycles; 8% lost. estimated prosthesis height mass approximately ${26}.{5} {cm}$ notation="LaTeX">${2}.{3} {kg}$ . Nonetheless, further necessary realise prototype bench in-vivo testing. By mimicking torque efficiently storing returning at joint, this new design may contribute reducing walking.